a) Field of the Invention
This invention relates to a lead-free solder which has mechanical properties as good as those of conventional Pb-Sn solder.
b) Description of the Prior Art
Pb--Sn alloys of eutectic or near-eutectic composition are well known as representative solders. Zn--Cd alloys, which have a greater strength than Pb--Sn eutectic solders, are also known. Amid the increased concern with environmental protection in recent years, the harmfulness of lead and the noxious effect of vaporized cadmium on workers have become a problem with the former and latter solders, respectively, and a solder replacing them is needed.
To meet this need, zinc or tin base solders, which contain neither harmful lead nor cadmium, were proposed. The solders hitherto proposed, however, do not have mechanical properties as good as conventional Pb--Sn solders. 3.5 Ag--Sn solder, for example, has a problem of a low tensile strength, though it has a satisfactory elongation. In this present situation, a solder which does not contain harmful lead or cadmium and has both a satisfactory high tensile strength and a satisfactory high elongation is desired.